The present invention relates to a conveyor system for supplying small parts to a chain assembling unit, the system comprising a track system transporting the small parts, and a feed device loading the track system with the small parts.
One decisive factor regarding the producible number of chain members in a chain assembling unit considerably depends on the capacity of the conveyor or feed devices. These conveyor devices must supply workpieces, in particular small chain parts such as bolts, sleeves or plates, etc., in adequate quantities for the joining operation. For a smooth joining operation, the conveyor system must have a high availability. To achieve such an availability, the prior art has suggested various. possible solutions, e.g. a redundant use of feed devices, a complete separation of the functions storing, conveying, organizing the joining process by presorting the components, etc. A presently preferred device in the field of chain assembly is a vibration type spiral conveyor which is particularly suited for supplying sleeves and bolts. However, these systems have also their limits, especially when a diameter ratio between 1 and 1.5 prevails in the transportation of cylindrical components. With such dimensions the components tend to get jammed in the baffles, increasingly resulting in disturbances. Numbers of pieces of more than 350 pieces/min are presently standard in the assembly of chains. However, the limiting factor in this system is most of the time the conveyor system, for recently developed joining methods could be carried out at a much higher number of pieces.
It is therefore the object of the present invention to provide a conveyor system which while being of a simple and inexpensive construction provides for a high availability of small parts.
This object is achieved according to the invention in that the track system comprises at least two loading tracks which can be loaded by the feed device with small parts, and at least one feed track which passes the small parts onwards to the chain assembling unit and communicates with at least one corresponding loading track, the number of the feed tracks being smaller than the number of the loading tracks, and the at least one feed track being selectively connectable to at least one other corresponding loading track for conveying the small parts.
This means that the feed device has e.g. twice the number of loading tracks, whereas only specific loading tracks communicate with a corresponding feed track. The feed track can be switched over or connected to another loading track under the most different circumstances and needs. In the event of disturbances in a loading track communicating with the feed track, another loading track is switched to. The disturbance in the now uncoupled loading track can then be remedied independently of the flow of material. Thus the loading tracks not participating in the conveying action at the moment serve as a buffer which will take part in the conveying operation through a corresponding connection to the feed track, e.g. in the event of disturbance or by a deliberate switching action performed by the user. At the same time, the feed device then performs again the continuous filling of the loading track. The question with which loading track a feed track is communicating at the moment may depend on many criteria, and the connection may be controlled manually or automatically. The connection of the loading tracks to the feed tracks, as well as the closing of the loading tracks not communicating with the feed tracks at the moment can be controlled in many ways.
Such a construction is also possible within a very confined constructional space, and only one loading-track length is needed for maintaining or ensuring a safe loading as well as an adequate availability in the case of a switching of the feed track.
Preferably, a shunt device may be provided between the loading tracks and the feed tracks for selectively connecting at least one specific loading track to at least one specific feed track. The shunt device must be designed such that it prevents a further outflow from the currently connected loading track or just waits until the same has been completed entirely, and then passes to another loading track. Such shunt devices may be of a very simple construction; that is why they can work very precisely and very rapidly. Consequently, even at a very fast conveying rate an exact switching operation is possible.
Although other assignments are feasible, the conveyor system can best be simplified according to one variant in that the number of the loading tracks is a multiple of the number of the feed tracks which can be divided by the number 2. It can thereby be ensured that switching, displacement or other paths that are as short as possible ensure a reliable reaction e.g. in the event of a disturbance.
It is thereby possible to position the respectively alternating tracks directly side by side without the arrangement of a further track thereinbetween.
To obtain reliable information as to when a feed track must be connected to another loading track, a monitoring device may be provided for monitoring the loading of the loading track and for supplying signals for a troublefree assignment of loading tracks and feed tracks. In the simplest case it can be checked whether a transportation flow is still maintained at the place of connection between loading track and feed track. As soon as small parts no longer pass through the place of connection, the feed track is changed to a preferred neighboring loading track. It may also be checked whether foreign matter, damaged parts or incorrectly positioned parts are located in the loading track. The signal supplied by the monitoring device can then be used via a corresponding processing unit as a control signal for an automatic change to another loading track.
In an advantageous embodiment, the shunt device comprises a channel system the inlets of which communicate with a respective loading track and whose at least one outlet communicates with a respective feed track, at least two inlet channels meeting each other at at least one channel crossing and being continued as a joint outlet channel. Thus the shunt device comprises a predetermined channel system by which the small parts are automatically guided in dependence upon the respectively connected loading track. Additional shunt elements will then provide for a corresponding transportation of the small parts. This can e.g. be carried out in that the shunt device comprises slider elements which for disabling or enabling an inlet channel and/or a loading track can be moved into or removed from said channel and/or track. Depending on the size of the small parts, pins or bolts of a simple design are also possible in this instance. These slider elements can be moved into an associated track or an associated channel at a specific angle or by reason of their shape such that a clamping action that is as great as possible is achieved if a small part is positioned in the displacement path of the slider element. As a result, the slider element must not exactly impinge within the gap between the small parts.
For reasons of safety each channel crossing of the shunt device may have assigned thereto a slider element for blocking or releasing the feeding channel. As a result, monitoring devices for monitoring the release of a channel crossing can be dispensed with, for it must be ensured that small parts are not supplied by both feeding channels at a channel crossing at the same time. This might cause a jam as well as an interruption of the material flow.
In particular, a control device may be provided for controlling the shunt device in dependence upon the monitoring signal of the monitoring device. For reasons of wear such a control device could also permit a manual switching operation, so that, if possible, all of the loading tracks are evenly used.
Furthermore, the control device may be designed such that the connection of a loading track to a feed track will only be released if the at least one associated channel crossing of the shunt device is free from chain parts. The control device switches the shunt device either at the right time or with the help of additional elements in such a way that a collision is prevented in the area of the channel crossing.
The small parts can be conveyed in the loading tracks and the feed tracks in the most different ways. Although according to one embodiment a transportation by gravity is preferred for reasons of costs, a forced guidance by means of vibration or compressed air, etc. is also possible. With such a forced transportation the throughput could even be increased considerably. Of importance is above all that a continuous transportation is ensured by the design of the loading tracks and the feed tracks.
To convey a sufficient number of small parts onto the loading tracks, it has been found that a rotating conveying pot with internally arranged blades is in particular suited as a feed device, said pot conveying the small parts into that section of the loading tracks that is upwardly open at least in the front area. The loading tracks are then preferably arranged with their front portion in the area of the rotational axis within the conveying pot such that the small parts are conveyed into the loading tracks by means of the blades. Such a conveying pot has a much higher output than formerly used vibration conveyors and is extremely robust in addition. This means that it is insensitive to soiled parts and that foreign matter does not lead to a failure of the conveying pot. The conveying pot may also be equipped with sieves or sieve walls so that undesired small parts or dirt are removed automatically. Furthermore, any desired number of loading tracks may be arranged in parallel that are loadable with a sufficient number of small parts. Since insensitive small parts are most of the time used in the field of chain assembly, such a conveying pot is excellently suited for ensuring an extremely high availability.
Furthermore, a stripper element, in particular a stripper roller and/or slider, may be provided which in cooperation with the conveying pot is assigned to the front area of the loading tracks, with incorrectly oriented small parts being stripped off or slid in a correct orientation into the loading tracks. Thus, the stripper element supports the correct positioning of the small parts in the loading tracks; in particular, upright small parts should be turned over by such a stripper element.
A further simplification is achieved in that the loading tracks and/or the component comprising the channel system of the shunt device are designed as upwardly open groove tracks in a substantially joint basic body.